Angiographic system with automatic high/low pressure switching

ABSTRACT

An angiographic injector system includes a manifold and valve which selectively connects either a syringe pump or a low pressure system to a catheter which is inserted into a patient. The valve is normally biased to a state which connects the low pressure system to the catheter for pressure monitoring, saline flushing, or aspirating functions. When an injection is to be made, the valve automatically switches so that the low pressure system is disconnected and not exposed to high pressure, while the syringe pump is connected through the manifold to the catheter.

This is a Continuation of application Ser. No. 08/426,148, filed Apr.20, 1995, now abandoned.

REFERENCE TO COPENDING APPLICATIONS

Reference is made to the following applications which are filed on evendate with this application and are assigned to the same assignee: Thisapplication is a co-pending application of U.S. application Ser. No.08/426,149, "Dual Port Syringe", filed on Apr. 20, 1995; U.S.application Ser. No. 08/425,300, "Continuously Adjustable Variable FlowRate Radiographic Contrast Material Injector", filed on Apr. 20, 1995;and U.S. application Ser. No. 08/425,577, "Self-Purging AngiographicInjector", filed on Apr. 20, 1995, now U.S. Pat. No. 5,573,515.

BACKGROUND OF THE INVENTION

This invention relates to angiography and more specifically, theinjector used to inject a medical fluid such as radiographic contrastmaterial into living organisms.

One of the major systems in the human body is the circulatory system.The major components of the circulatory system are the heart, bloodvessels, and the blood, all of which are vital to the transportation ofmaterials between the external environment and the different cells andtissues of the human body.

The blood vessels are the network of passageways through which the bloodtravels in the human body. Specifically, arteries carry the oxygenatedblood away from the left ventricle of the heart. These arteries arealigned in progressively decreasing diameter and pressure capabilityfrom the aorta, which carries the blood immediately out of the heart toother major arteries, to smaller arteries, to arterioles, and finally totiny capillaries, which feed the cells and tissues of the human body.Similarly, veins carry the oxygen depleted blood back to the rightatrium of the heart using a progressively increasing diameter network ofvenules and veins.

If the heart chambers, valves, arteries, veins or other capillariesconnected thereto are either abnormal (such as from a birth defect),restricted (such as from atherosclerotic plaque buildup), ordeteriorating (such as from aneurism formation), then a physician mayneed to examine the heart and connected network of vessels. Thephysician may also need to correct any problems encountered during theexamination with a catheter or similar medical instrument.

Angiography is a procedure used in the detection and treatment ofabnormalities or restrictions in blood vessels. During angiography, aradiographic image of a vascular structure is obtained by injectingradiographic contrast material through a catheter into a vein or artery.The vascular structures fluidly connected with the vein or artery inwhich the injection occurred are filled with contrast material. X-raysare passed through the region of the body in which the contrast materialwas injected. The X-rays are absorbed by the contrast material, causinga radiographic outline or image of the blood vessel containing thecontrast material. The x-ray images of the blood vessels filled withcontrast material are usually recorded onto film or videotape and aredisplayed on a fluoroscope monitor.

Angiography gives the doctor an image of the vascular structures inquestion. This image may be used solely for diagnostic purposes, or theimage may be used during a procedure such as angioplasty where a balloonis inserted into the vascular system and inflated to open a stenosiscaused by atherosclerotic plaque buildup.

Currently, during angiography, after a physician places a catheter intoa vein or artery (by direct insertion into the vessel or through a skinpuncture site), the angiographic catheter is connected to either amanual or an automatic contrast injection mechanism.

A simple manual contrast injection mechanism typically has a syringe anda catheter connection. The syringe includes a chamber with a plungertherein. Radiographic contrast material is suctioned into the chamber.Any air is removed by actuating the plunger while the catheterconnection is facing upward so that any air, which floats on theradiographic contrast material, is ejected from the chamber into theair. The catheter connection is then attached to a catheter that ispositioned in a vein or artery in the patient.

The plunger is manually actuated to eject the radiographic contrastmaterial from the chamber, through the catheter, and into a vein orartery. The user of the manual contrast injection mechanism may adjustthe rate and volume of injection by altering the manual actuation forceapplied to the plunger.

Often, more than one type of fluid injection is desired, such as asaline flush followed by the radiographic contrast material. One of themost common manual injection mechanisms used today includes a valvemechanism which controls which of the fluids will flow into the valvingmechanism and out to the catheter within the patient. The valvemechanism contains a plurality of manual valves that the user operatesmanually to open and close that particular fluid channel. When the usersuctions or injects contrast fluid into the chamber, the fluid is pulledfrom the valve mechanism via the open valves. By changing the valvepositions, another fluid may be injected.

These manual injection mechanisms are typically hand actuated. Thisallows user control over the quantity and pressure of the injection.However, all of the manual systems are only capable of injecting theradiographic contrast material at maximum pressure that can be appliedby the human hand (i.e., 150 p.s.i). Also, the quantity of radiographiccontrast material is typically limited to a maximum of about 12 cc.Finally, there are no safety limits on these manual contrast injectionmechanisms which act to restrict or stop injections that are outside ofreasonable parameters (such as rate or pressure) and no active sensorsto detect air bubbles or other hazards.

Currently used motorized injection devices consist of a syringeconnected to a linear actuator. The linear actuator is connected to amotor, which is controlled electronically. The operator enters into theelectronic control a fixed volume of contrast material to be injected ata fixed rate of injection. The fixed rate of injection consists of aspecified initial rate of flow increase and a final rate of injectionuntil the entire volume of contrast material is injected. There is nointeractive control between the operator and machine, except to start orstop the injection. Any change in flow rate must occur by stopping themachine and resetting the parameters.

The lack of ability to vary the rate of injection during the injectionresults in suboptimal quality of angiographic studies. This is becausethe optimal flow rate of injections varies considerably betweenpatients. In the cardiovascular system, the rate and volume of contrastinjection is dependent on the size of and blood flow rate within thechamber or blood vessel being injected. In many or most cases, theseparameters are not known precisely. Moreover, the optimal rate ofinjection can change rapidly, as the patient's condition changes inresponse to drugs, illness, or normal physiology. Consequently, theinitial injection of contrast material may be insufficient in flow rateto outline the structure on x-ray imaging, necessitating anotherinjection. Conversely, an excessive flow rate might injure the chamberor blood vessel being injected, cause the catheter to be displaced (fromthe jet of contrast material exiting the catheter tip), or lead to toxiceffects from contrast overdose (such as abnormal heart rhythm).

At present, the operator can choose between two systems for injectingcontrast material: a manual injection system which allows for avariable, operator interactive flow rate of limited flow rate and apreprogrammed motorized system without operator interactive feedback(other than the operator can start/stop the procedure).

SUMMARY OF THE INVENTION

The present invention is an angiographic injection system which includesboth high pressure and low pressure systems. The high pressure systemincludes a motor driven injector pump which supplies radiographiccontrast material under high pressure to a catheter. The low pressuresystem includes, for example, a pressure transducer for measuring bloodpressure and a pump which is used to both for delivering saline solutionto the patient and for aspirating waste fluid. In the present invention,a manifold is connected to the syringe pump; the low pressure system,the catheter which is inserted into the patient. A valve associated withthe manifold is normally maintained in a first state which connects thelow pressure system to the catheter through the manifold. When pressurefrom the syringe pump reaches a predetermined level, the valve switchesto a second state which connects the syringe pump to the catheter, whiledisconnecting the low pressure system from the catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a preferred embodiment of theangiographic injector system of the present invention.

FIGS. 2A-2G are diagrams illustrating operations of the system of FIG.1.

FIG. 3 is an electrical block diagram of the control system of theinjector system of FIG. 1.

FIG. 4 illustrates front panel controls and displays of a preferredembodiment of the injector system of the present invention.

FIGS. 5A and 5B are side and partial top perspective views of the remotecontrol of the system of FIG. 1.

FIG. 6 is a perspective view of a foot operated remote control.

FIGS. 7A-7D illustrate the operation of the inlet check valve andmanifold during contrast fill, air purge, and patient inject operations.

FIGS. 8A-8C illustrate operation of the inlet check valve in greaterdetail.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows angiographic injector system 10 for injecting radiographiccontrast material into a blood vessel under interactive physiciancontrol. System 10 includes main console 12, hand held remote control14, syringe holder 16, syringe body 18, syringe plunger 20, radiographicmaterial reservoir (bottle) 22, one-way valve 24, manifold 26, highpressure tube 28, catheter 30, patient medication port 32, three-waystop-cock 34, T-connector 36, pressure transducer 38, stop-cock 40,tubing 42, peristaltic pump 44, saline check valve 46, waste check valve48, saline bag 50, waste bag 52, and bag support rack 54.

Console 12 houses the electrical controls for system 10, together withthe motors which drive piston 20 and peristaltic pump 44. On the frontsurface of console 12, user interface 54 provides control switches 56and display 58 through which the user may enter control settings andmonitor the operational state of system 10.

Remote control 14 is connected to console 12 by cable 60 (although inother embodiments remote control 14 may be connected by a wirelessconnection such as an RF, infrared optic, or ultrasonic link). Remotecontrol 14 is, in the embodiment shown in FIG. 1, a hand-held controlwhich includes reset and saline push button switches 62 and 64,respectively, and flow rate control lever or trigger 66. By squeezingtrigger 66, the user can provide a command signal to console 12 toprovide a continuously variable injection rate.

Syringe holder 16 projects from the left hand side of console 12.Syringe holder 16 is preferably a clear material, and includes a halfcylindrical back shell 68, a half cylindrical front door 70 (which isshown in open position in FIG. 1), and reservoir holder 72.

Syringe 18 is a transparent or translucent plastic cylinder having itsopen end 74 connected to console 12. Closed end 76 of syringe 18contains two ports: upper port 78 and lower port 80.

Plunger 20 is movable within syringe body 18. Plunger 20 is connectedto, and driven by a motor located within console 12.

Radiographic contrast material reservoir 22 is connected through one-waycheck valve 24 to upper port 78. Radiographic contrast material is drawnfrom reservoir 22 through check valve 24 and upper port 78 into thepumping chamber defined by syringe body 18 and plunger 20. Check valve24 is preferably a weighted one-way valve which permits air to flow fromsyringe body 18 back into reservoir 22, but will not permit radiographiccontrast material to flow from syringe body 18 to reservoir 22. Thispermits automatic purging of air from the system, as will be describedin more detail later.

Lower port 80 of syringe body 18 is connected to manifold 26. Manifold26 includes a spring biased spool valve which normally connectstransducer/saline port 82 and patient port 84. When radiographiccontrast material is to be injected, the pressure of the radiographicmaterial causes the spool valve to change states so that lower port 80is connected to patient port 84.

High pressure tube 28 is a flexible tube which connects patient port 84to catheter 30. Three-way stop-cock 34 is located at the distal end oftube 28. Rotatable luer lock connector 86 is connected to stop-cock 34and mates with luer connector 88 at the proximal end of catheter 30.Stop-cock 34 either blocks flow between tube 28 and catheter 30, permitsflow, or connects medication port 32 to catheter 30.

In addition to injecting radiographic material into a patient throughcatheter 30, system 10 also permits other related functions to beperformed. A device for delivering the patient medication (not shown inFIG. 1) may be connected to medication port 32 when medication is to bedelivered through catheter 30 to the patient.

When catheter 30 is in place in the patient, and an injection ofradiographic contrast material is not taking place, pressure transducer38 monitors the blood pressure through the column of fluid which extendsfrom catheter 30, tube 28, patient port 84, manifold 26,transducer/saline port 82, tubing 90, T-connector 36, and tubing 92.Transducer 38 has an associated stop-cock 40 which allows transducer 38to be exposed to atmospheric pressure during calibration and also allowsfor removal/expulsion of trapped air so the dome chamber of transducer38 can be flushed with saline.

Peristaltic pump 44 supplies saline solution from bag 50 through salinecheck valve 46, tubing 42, T-connector 36 and tubing 90 to saline port82. When peristaltic pump 44 is operating to supply saline solution, thesaline solution is supplied through manifold 26 to patient port 84 andthen through tube 28 to catheter 30.

Peristaltic pump 44 also operates in an opposite direction to draw fluidfrom catheter 30 and through tube 28, manifold 26, tubing 90,T-connector 36 and tubing 42 to waste check valve 48 and then into wastecollection bag 52.

In a preferred embodiment of the present invention, syringe body 18,manifold 26, tube 28, catheter 30, T-connector 36, tubing 42, checkvalves 46 and 48, bags 50 and 52, and tubing 90 and 92 are alldisposable items. They must be installed in system 10 each time anangiography procedure is to be performed with a new patient. Once system10 is set up with all the disposable items installed, door 70 is closed,and syringe body 18 filled with contrast material and purged of air, theuser (typically a physician) enters into system 10 the safety parametersthat will apply to the injection of radiographic contrast material.These safety parameters typically include the maximum amount ofradiographic contrast material to be injected during any one injection,the maximum flow rate of the injection, the maximum pressure developedwithin syringe body 18, and the maximum rise time or acceleration of theinjection. To actuate an injection of contrast material, the useroperates remote control 14 by squeezing trigger 66. Within the presetsafety parameters, system 10 causes the flow rate of the injection toincrease as the force or distance of travel of trigger 66 is increased.

Typically, the user will meter the amount and rate of contrast materialinjected based upon continuous observation of the contrast outflow intothe structure being injected using fluoroscopy or other imaging methods.System 10 allows the user to tailor the contrast injections to the needsof the patient, thereby maximizing the quality of the procedure,increasing the safety, and reducing the amount of contrast materialrequired to perform the fluoroscopic examination.

FIGS. 2A-2G are diagrams illustrating fluid flow paths during sevendifferent operations of system 10. Those operations are contrast fill(FIG. 2A), air purge (FIG. 2B), patient inject (FIG. 2C), patientpressure (FIG. 2D), saline flush (FIG. 2E), aspirate waste (FIG. 2F),and medicate patient (FIG. 2G).

The contrast fill operation illustrated in FIG. 2A involves the fillingof syringe body 18 with radiographic contrast material from reservoir(contrast media supply) 22. The contrast fill operation is performedduring initial set up of system 10, and may be repeated during operationof system 10 whenever syringe body 18 is running low on radiographiccontrast material.

During initial set up of system 10, plunger 20 is initially driven toits furthest forward position adjacent closed end 76 of syringe body 18.This will expel to the atmosphere the majority of the air which islocated within syringe body 18.

Plunger 20 is then retracted, which creates a vacuum within syringe body18 which draws contrast material from reservoir 22 through check valve24 into syringe body 18 through upper port 78.

The Contrast Fill operation typically will result in some air beingdrawn into or remaining within syringe body 18. It is important, ofcourse, to prevent air from being injected into the patient throughcatheter 30. That is the purpose of the Air Purge operation shown inFIG. 2B. Also, the location of two ports at different elevations allowsfor a greater amount of safety in preventing air bubbles in theinjection.

During the Air Purge operation, plunger 20 travels forward to expeltrapped air within syringe body 18. The air, being lighter than thecontrast material, gathers near the top of syringe body 18. As plunger20 moves forward, the air is expelled from syringe body 18 through upperport 78 and one-way valve 24. In the embodiment illustrated in FIG. 2B,one-way valve 24 is a weighted one-way valve which allows flow ofradiographic contrast material from reservoir 22 to upper port 78, butwill not allow radiographic contrast material to flow in the oppositedirection from upper port 78 to reservoir 22. Valve 24 will, however,allow air to flow from port 78 to reservoir 22. As soon as radiographiccontrast material begins flowing out of syringe body 18 through upperport 78 to valve 24, valve 24 closes to prevent any further flow towardreservoir 22.

Valve 24 can also, in alternative embodiments, can be a solenoidactuated or motor driven valve operated under control of the electriccircuitry within console 12. In either case, valve 24 is capable towithstanding the relatively high pressures to which it will be subjectedduring the inject operation. Preferably, valve 24 is capable ofwithstanding static fluid pressures up to about 1200 p.s.i.

FIG. 2C illustrates the Patient Inject operation. Plunger 20 travelsforward under the interactive control of the user, who is controllingtrigger 66 of remote control 14. The movement of plunger 20 createshydraulic pressure to force contrast material out of syringe body 18through lower port 80 and through manifold 26 and high pressure tube 28into catheter 30. As shown in FIG. 2C, syringe lower port 80 and patientport 84 are connected for fluid flow during the patient injectoperation.

Manifold 26 contains a valve which controls the routing of fluidconnections between patient port 84 and either syringe bottom port 80 ortransducer/saline port 82. In one embodiment of the present invention,manifold 26 includes a spool valve which is spring biased so thatpatient port 84 is normally connected to transducer/saline port 82 (asillustrated in FIGS. 2A and 2B). When the pressure at syringe bottomport 80 builds with the movement of plunger 20 forward, the bias forceagainst the spool valve is overcome so that syringe bottom port 80 isconnected to patient port 84, and transducer/saline port 82 isdisconnected the valve within manifold 26 protects pressure transducer38 from being exposed to the high pressure generated by the patientinject operation.

The spool valve opens automatically during the patient inject operationin response to increase pressure exerted on it from the syringe lowerport 80. The spool valve closes and returns to its original positionallowing for connection of patient port 84 to transducer 38 when aslight vacuum is applied by retraction of plunger 20 at the end of eachPatient Inject operation.

In an alternative embodiment, the valve within manifold 26 is anelectromechanical or motor driven valve which is actuated at appropriatetimes to connect either syringe lower port 80 or transducer/saline port82 to patient port 84. The actuator mechanism is controlled by console12. Once again in this alternative embodiment, the valve protectspressure transducer 38 from being exposed to high pressure.

FIG. 2D illustrates the Patient Pressure operation. System 10 allows forreading of the patient's blood pressure, which is monitored throughcatheter 30. Patient blood pressure can be monitored through the use ofpressure transducer 38 at any time except during the patient inject,saline flush, and waste aspirate operations. The pressure reading beingproduced by pressure transducer 38 may be normalized by manually openingstop-cock 40 and closing stop-cock 34 to expose pressure transducer 38to atmospheric pressure.

During the Saline Flush operation illustrated in FIG. 2E, salinesolution is used to flush all of the internal lines, pressure transducerchamber 38, tube 28, and catheter 30. As shown in FIG. 2E, peristalticpump 44 is operating in a direction which causes saline solution to bedrawn from bag 50 through check valve 46 and through tubing 42 to salineport 82. Manifold 26 connects saline port 82 to patient port 84 so thatsaline solution is pumped out of patient port 84 and through tube 28 andcatheter 30.

During the Aspirate Waste operation, patient port 84 is again connectedto saline port 82. During this operation, peristaltic pump 44 isoperating in the opposite direction from its rotation during the salineflush operation. As a result, patient fluids are aspirated from patientport 84 to saline port 82 and then through tubing 42 and check valve 48into waste collection bag 52. Peristaltic pump 44 acts as a valvepinching/occluding tubing 42 and preventing back flow to/from saline andwaste containers 50 and 52 in conjunction with check valves 46 and 48.

With catheter 30 in place within the patient, it may be desirable tosupply patient medication. System 10 allows for that option by providingpatient medication port 32. As shown in FIG. 2G, when stop-cock 34 isopen, a medication source connected to port 32 will be connected topatient port 84, and thereby to catheter 30. During the medicate patientoperation, peristaltic pump 44 and plunger 20 are not moving.

FIG. 3 is an electrical block diagram of the control system whichcontrols the operation of angiographic injector system 10. Theelectrical control system includes digital computer 100, which receivesinput signals from remote control 14 and front panel controls 56 throughinterface 102, and provides signals to display 58 to display operationdata, alerts, status information and operator prompts.

Computer 100 controls the motion of plunger 20 through a motor drivecircuit which includes motor 104, motor amplifier 106, tachometer 108,potentiometer 110, a rectifier 112, pressure sensing load cell 114, andA/D converter 160.

Motor amplifier 106 provides a Drive 1 signal to motor 104 in responseto Control Voltage, Fwd/Rev, and /Brake signals from computer 100 and aspeed feedback signal from tachometer 108 through rectifier 112. Theoutputs of tachometer 108 and potentiometer 110 are supplied to computer100 through A/D converter 116 as Speed Monitor and Position Monitorsignals. These allow computer 100 to check motor speed, motor direction,and position (volume is a calculated value).

Pressure sensor 114 senses motor current or plunger force in order tomeasure the pressure being applied to the radiographic contrast materialwithin syringe body 18. This Pressure Monitor Signal is supplied throughA/D converter 116 and interface 102 to computer 100.

Peristaltic pump 44 is driven under the control of computer 100 throughpump motor 120, motor driver 122 and optical encoder 124. Computer 100provides Saline (Forward) and Waste (Reverse) drive signals to motordriver 122 to operate pump motor 120 in a forward direction for salineflush and a reverse direction for waste aspiration. Optical encoder 124provides the Speed Direction Monitor signal to interface 102 whichindicates both the speed and the direction of rotation of pump motor120.

FIG. 3 illustrates an embodiment of the control system in which valvemotor 130 is used to actuate valves such as one-way valve 24 and thevalve within manifold 26. In this embodiment, computer 100 controlsvalve motor 130 through motor driver 132, and monitors position througha Position Monitor feedback signal from potentiometer 134. In thisparticular embodiment, valve motor 130 is a stepper motor.

Computer 100 monitors temperature of the contrast material based upon aTemp Monitor signal from temperature sensor 140. Temperature sensor 140is preferably positioned near syringe body 18. If the temperature beingsensed by temperature sensor 140 is too high, computer 100 will disableoperation motor 104 to discontinue patient injection. If the temperatureis to low, computer 100 provides a /Temp Enable drive signal to heaterdrive 150, which energizes heater 152. In one preferred embodiment,heater 152 is a resistive film heater which is positioned within syringeholder 116 adjacent to syringe body 18.

Computer 100 also receives feedback signals from contrast bottle sensor160, forward limit sensor 162, reverse limit sensor 164, syringe missingsensor 166, chamber open sensor 168, no contrast bubble detector 170,and air in line bubble detector 172.

Contrast bottle sensor 160 is a miniature switch located withinreservoir holder 72. The state of the Contrast Bottle Present signalfrom sensor 160 indicates whether a reservoir 22 is in position withinholder 72. If reservoir 22 is not present, computer 100 will disable thefill operation.

Forward limit and reverse limit sensors 162 sense the end limitpositions of plunger 20. When plunger 20 reaches its forward limitposition, no further forward movement of plunger 20 is permitted.Similarly, when reverse limit sensor 164 indicates that plunger 20 hasreached its reverse limit position, no further reverse movements arepermitted.

Syringe missing sensor 166 is a miniature switch or infraredemitter/detector which indicates when syringe body 18 is not in positionwithin syringe holder 16. If syringe body 18 is not in position, allmovement functions are disabled except that plunger 20 can move to itsreverse limit position (i.e., return to zero).

Chamber open sensor 168 is a miniature switch or infraredemitter/detector which senses when door 70 of syringe holder 16 is open.When the signal from sensor 168 indicates that door 70 is open, allmovement functions are disabled. Only when door 70 is closed and lockedmay any movement be allowed. When door 70 is indicated as closed andsensor 166 indicates the syringe body 18 is in position, other normalfunctions of the system 10 can proceed.

Bubble detector 170 is positioned between reservoir 22 and top port 78,and is preferably an infrared emitter/detector which senses air bubbles.If an air bubble is sensed in the flow path between reservoir 22 and topport 78 during a fill operation, the fill operation is disabled until anew reservoir is connected.

Bubble detector 172 is positioned to sense air bubbles in high pressureline 28. It is preferably an infrared emitter/detector type of bubbledetector. Any air bubble which is sensed in high pressure line 28results in the disabling of all fluid push out functions, whether thefluid is saline solution from peristaltic pump 44 or contrast materialfrom syringe body 18.

The control system of FIG. 3 also includes the capability to provide acontrol signal to x-ray equipment through relay 180 which is controlledby computer 100. In addition, computer 100 receives data from bloodpressure transducer 38 and from an electrocardiograph (ECG) system,which is separate from injector system 10. The Pressure and ECG signalsare received through signal conditioners and A/D converter 190, and aretransferred to computer 100. The ECG signal is used by computer 100 inone preferred embodiment, to synchronize operation of motor 104 (andthus the Patient Inject operation) with heart beats.

Blood flow to the heart occurs predominantly in diastole (when the heartis between contractions). Continuous injection of contrast materialresults in spillage of the contrast material into the aorta duringsystole (during contraction). By injecting primarily during diastole,contrast dosage can be reduced without impairing the completeness of thecontrast injection into the coronary artery.

In a preferred embodiment, the injection of radiographic contrastmaterial is synchronized to the coronary artery blood flow. The timeperiods of systole and diastole are determined using anelectrocardiographic (ECG) electrical signal, arterial blood pressurewaveform analysis, or other timing based on the heart rate. Bycontrolling speed of motor 104, speed and therefore movement of plunger20, the injection of contrast material is interrupted during the periodof systole, which reduces or stops contrast injection during this time.In combination with remote control 14, the operator can vary the rate ofcontrast injection into the coronary artery while computer 100automatically pulses the contrast injection to the cardiac cycle

The inertial forces of the moving contrast material and expansion of thecontainers and tubing holding the contrast material and transmitting itto the patient can cause a phase lag between movement of plunger 20within syringe body 18 and movement of contrast material out of catheter30 into the patient. To adjust to the phase lag between the plunger 20movement and contrast expulsion into the patient, a variable time offsetcan be entered through control panel 54 such that the timing of thecardiac cycle can be offset by a selected time. Since the magnitude ofthe phase lag may be dependent on the frequency of the heart rate, analgorithm within computer 100 continuously and automatically adjusts themagnitude of the time offset, based on the instantaneous heart rateduring the injection of contrast material.

FIG. 4 shows one embodiment of control panel 54 which illustrates thefront panel control switches 56 and display 58 of one embodiment of thepresent invention. Front panel control switches 56 include SetUp/Fill/End switch 200, Purge switch 202, Aspirate switch 204, Salineswitch 206, Enable OK switch 208, Injection Volume Limit switches 210aand 210b, Injection Flow Rate limit switches 212a and 212b, InjectionPressure Limit switches 214a and 214b, Rise Time switches 216a and 216b,OK switch 218, Injection Range Toggle switch 220, Large Injection OKswitch 222, and Stop switch 224.

Set Up/Fill/End switch 200 is a momentary push button switch. When it isfirst activated, the user will be notified to place syringe 18 insyringe holder 16. When syringe 18 has been placed in syringe holder 16(which is indicated to computer 100 by sensor 166), the user will beinstructed to close and lock the chamber (i.e., to close door 70).Plunger 20 is moved to its full forward position expelling all airwithin the syringe. Display 58 then indicates to the operator thatcontrast reservoir 22 should be connected. Once contrast reservoir 22has been put in place, the operator is requested to depress OK switch218, at which time plunger 20 will retract at a set rate (preferablycorresponding to a flow rate of 10 ml per second) to the maximum syringevolume. If the real speed (as indicated by feedback to computer 100 fromA/D converter 116) is greater than the set speed, system 10 will stop.

Once plunger 20 is at its rearward most position, motor 104 is actuatedto move plunger 20 forward to purge all air bubbles. Pressure sensor 114provides an indication of when one-way valve 24 is closed and pressureis beginning to build up within syringe body 18. Once the purge iscompleted, the total volume injected and the number of injectionscounter is reset.

The actuation of switch 200 also allows for full retraction anddisengagement of plunger 20 from syringe body 18.

Purge switch 202 is a protected momentary push button switch. Whenactivated, Purge switch 202 causes plunger 20 to move forward to expelair through top port 78. The forward movement of plunger 20 is limitedand stopped when a predetermined pressure within syringe 18 is reached.This is sensed by pressure sensor 114. The purge operation which isinitiated by Purge switch 202 will expel air within syringe 20. The usermay also use Purge switch 202 to purge fluid through patient port 84 bydepressing and holding Purge switch 202 continuously on.

Aspirate switch 204 is a momentary push button switch which causescomputer 100 to activate pump motor 120 of peristaltic pump 44. Pumpmotor 120 is operated to aspirate catheter 30 at a set speed, with theaspirated fluid being collected in waste bag 52. All other motionfunctions are disengaged during aspiration. If the real speed of motor120 is greater than a set speed, computer 100 will stop motor 120.

Saline switch 206 is an alternate action switch. Pump motor 120 isactivated in response to Saline switch 206 being pushed on, and salinesolution from bag 50 is introduced into manifold 26 and catheter 30 at aset speed. If Saline switch 206 is not pushed a second time to stop theflow of saline solution within 10 seconds, computer 100 automaticallystops pump motor 120. If a time-out is reached, Saline switch 206 mustbe reset to its original state prior to initiating any further actions.

Enable OK switch 208 is a momentary push button switch. After the systemhas detected a disabling function at the end of an injection other thana limit, Enable OK switch 208 must be activated prior to activating OKswitch 218 and initiating any further function.

Injection Volume Limit keys 210a and 210b are pushed to either increaseor decrease the maximum injection volume that the system will injectduring any one injection. Key 210a causes an increase in the maximumvolume value, and key 210b causes a decrease. Once the maximum injectionvolume limit has been set, if the measured volume reaches the set value,computer 100 will stop motor 104 and will not restart until OK switch218 has been depressed. If a large injection (i.e., greater than 10 ml)has been selected, OK switch 218 and Large Injection OK switch 220 mustboth be reset prior to initiating the large injection.

Injection Flow Rate Limit keys 212a and 212b allow the physician toselect the maximum flow rate that the system can reach during any oneinjection. If the measured rate (which is determined by the feedbacksignals from tachometer 108 and potentiometer 110) reaches the setvalue, computer 100 will control motor 104 to limit the flow rate to theset value.

Injection Pressure Limit keys 214a and 214b allow the physician toselect the maximum pressure that the system can reach during any oneinjection. If the measured pressure, as determined by pressure sensor114, reaches the set value, computer 100 will control motor 104 to limitthe pressure to the injection pressure limit. The injection rate willalso be limited as a result.

Rise Time keys 216a and 216b allow the physician to select the rise timethat the system will allow while changing flow rate during any oneinjection. Computer 100 controls motor 104 to limit the rise time to theset value.

In alternative embodiments, keys 210a-210b, 212a-212b, 214a-214b, and216a-216b can be replaced by other devices for selecting numericalvalues. These include selector dials, numerical keypads, and touchscreens.

OK switch 218 is a momentary push button switch which resets functionsand hardware sensors. In response to OK switch 218 being activated,computer 100 controls display 58 to ask the operator to acknowledge thatthe correct function has been selected. Activation of OK switch 218causes the status to be set to Ready.

Injection Range switch 220 is a toggle switch. Depending on whetherswitch 220 is in the "small" or "large" position, it selects either ahigh or a low injection volume range for the next injection.

Large Injection OK switch 222 is a momentary push button switch. Whenthe large injection range has been selected by injection range switch220, the Large Injection OK button 222 must be activated to enable OKswitch 218. OK switch 218 must be activated prior to each injection. Onlarge volume injections, the user is required to verify the volumeselected by activating first Large Injection OK switch 222 and then OKswitch 218.

Stop switch 224 is a momentary push button switch. When stop switch 224is pushed, it disables all functions. Display 58 remains active.

Display panel 58 includes Set-Up display 250, Status display 252, Alertsdisplay 254, Limits display 256, total number of injections display 260,total volume injection display 262, flow rate display 264, injectionvolume display 266, injection volume limit display 268, injection ratelimit display 270, pressure limit display 272, rise time minimum display274, large injection display 276, and real time clock display 278.

Set-Up display 250 contains a series of messages which are displayed asthe operator goes through the set up procedure. The display of messagesin set up display 250 are initiated by the actuation of set up switch200 as described previously.

Status display 252 provides a flashing indication of one of severaldifferent operating conditions. In the embodiment shown in FIG. 4, thesestatus conditions which can be displayed include "Ready", "Set-Up","Injecting", "Filling", "Flushing", and "Aspirating".

Alerts display 254 and Limits display 256 notify the operator ofconditions in which system 10 has encountered a critical controlparameter and will disable operation, or has reached an upper or lowerlimit and will continue to function in a limited fashion, or has reachedan upper or lower limit and will continue to operate.

Total number of injections display 260 displays the total number ofinjections (cumulative) given for the current patient case. Thecumulative total volume injected during the current patient case isdisplayed by total volume display 262.

Displays 264 and 266 provide information on the current or lastinjection. Display 264 shows digital value of the real time flow rate tothe patient during injection. Once the injection is completed, the valuedisplayed on display 264 represents the peak flow rate reached duringthat injection. Display 266 shows the digital value of the volumeinjected during the most recent injection.

Display 268 displays the digital value of the maximum injection volumeselected by operation of switches 210a and 210b. Similarly, display 270shows the digital value of the maximum flow rate that the system willallow, as selected by switches 212a and 212b.

Display 272 shows the digital value of the maximum pressure that thesystem will allow to be developed in syringe 18. The pressure limit isselected by switches 214a and 214b.

Display 274 displays the minimum rise time that the system will allowwhile changing flow rate. The minimum rise time is selected throughswitches 216a and 216b.

Large injection display 276 provides a clear indication when the largeinjection scale has been selected by the operator.

Real-time clock display 278 shows the current time in hours, minutes,and seconds.

FIGS. 5A and 5B show remote control 14 which includes main housing 300,which is designed to conform to the users hand. Trigger 66 is movablewith respect to housing 300, and the position of trigger 66 generates acommand signal which is a function of trigger position. In oneembodiment, trigger 66 is linked to a potentiometer within housing 300.The command signal controls the injunction flow rate or speed. The flowrate is directly proportional to trigger position.

Reset switch 62 is a momentary push button switch whose function isidentical to that of OK switch 218. Alternatively, Reset switch 62 mayalso be labeled "OK".

Saline switch 64 on remote control 14 is an alternate action push buttonswitch which is pushed to turn on and pushed again to turn off. Thefunction of Saline switch 62 is the same as that of Saline switch 206 onfront panel 54.

As illustrated in another embodiment of the present invention, analternative remote control 14' in the form of a foot pedal is usedinstead of the hand held remote control 14 illustrated in FIG. 1 and inFIGS. 5A and 5B. Foot pedal remote control 14' includes foot operatedspeed pedal or trigger 66' for providing a command signal, as well asReset or OK switch 62' and Saline switch 64'. Covers 310 and 312 protectswitches 62' and 64' so that they can only be actuated by hand and notaccidentally by foot. Foot pedal remote control 14' is connected toconsole 12 by cable 60', but could alternatively be connected by awireless link.

FIGS. 7A-7D and FIGS. 8A-8C illustrate the construction and operation ofone way valve 24 and manifold 26 during Contrast Fill, Air Purge andPatient Injection operation.

FIGS. 7A and 8A illustrate one way or check valve 24, manifold 26,syringe body 18, and plunger 20 during a Contrast Fill operation. Inletcheck valve of one way valve 24 includes weighted ball 350 which ispositioned at its lower seated position within valve chamber 352 inFIGS. 7A and 7B. Contrast material is being drawn into syringe body 18by the rearward movement of plunger 20. The contrast material flowsthrough passages 354 around ball 350 and into upper port 78.

Manifold 26 contains spring loaded spool valve 360, which includes spoolbody 362, shaft 364, O-rings 366, 368 and 370, bias spring 372, andretainer 374. As shown in FIG. 7A, during the Contrast Fill operation,bias spring 372 urges spool body 362 to its right-most position towardsyringe body 18. In this position, spool body 362 blocks lower port 80of syringe body 18 while connecting transducer saline port 82 to patientport 84 through diagonal passage 376. O-rings 366 and 368 on the onehand, and O-ring 370 on the other hand, are positioned on the oppositesides of diagonal passage 376 to provide a fluid seal.

FIGS. 7B and 8B illustrate the Air Purge operation. Syringe body 18 hasbeen filled with contrast fluid, but also contains trapped air. Plunger20 is driven forward to force the air out of syringe body 18 throughupper port 78 and through check valve 24. The force of the air may causea slight lifting of ball 350 in check valve 20. Ball 350, however, issufficiently heavy that the air being forced out of syringe body 18 andback toward reservoir 22 cannot lift ball 350 into its uppermost seatedposition where it would block the flow of air out of syringe body 18.

During the Air Purge operation, spool valve 360 is in the same positionas in FIG. 7A. Diagonal passage 376 connects transducer saline port 82with patient port 84. As a result, pressure monitoring by pressuretransducer 38 can be performed during the Air Purge (as well as theContrast Fill) operation.

FIGS. 7C and 8C illustrate the state of manifold 26 and check valve 24at the end of the Air Purge operation and at the beginning of a PatientInject operation.

In FIG. 7C, all air has been expelled from syringe body 18. Ball 350floats on the radiographic contrast material, so that when all air hasbeen removed and the radiographic contrast material begins to flow outof syringe body 18 and through upper port 78 to valve chamber 352, ball350 is moved upwards to its upper seated position. Ball 350 blocks anycontinued upward flow of radiographic contrast material, as isillustrated in FIGS. 7C and 8C.

In the state which is illustrated in FIG. 7C, the pressure withinsyringe body 18, and specifically the pressure in lower port 80 has notyet reached a level at which the bias force of spring 372 has beenovercome. As a result, spool body 362 has not yet moved to the left anddiagonal passage 376 continues to connect transducer saline port 82 withpatient port 84.

FIG. 7D illustrates the patient inject operation. Plunger 20 is movingforward, and inlet check valve 24 is closed. The pressure at lower port80 has become sufficiently high to overcome the bias force of spring372. Spool body 362 has been driven to the left so that lower port 80 isconnected to patient port 84. At the same time spool body 362 blockstransducer/saline port 82.

By virtue of the operation of spool valve 360, the high pressuregenerated by movement of plunger 20 and syringe body 18 is directlyconnected to patient port 84, while saline port 82 and pressuretransducer 38 are protected from the high pressure. The pressure toactuate may be variable and determined after manufacture by increasingor decreasing the syringe preload.

In conclusion, the angiographic injector system of the present inventionprovides interactive control of the delivery of radiographic contrastmaterial to a catheter through a user actuated proportional control.This allows the user to adjust the flow rate of contrast materialinteractively as needed and as the patient's condition changes.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. For example, syringe holder 16 may takeother forms, such as an end loaded cylinder. Similarly, manifold 26 cantake other configurations and can incorporate, for example, a part ofports 78 and 80.

What is claimed is:
 1. An angiographic injection system for use inconjunction with a catheter having a distal end for insertion into apatient and having a proximal end, the system comprising:a motor drivensyringe pump for supplying fluid under pressure; a low pressure system;a manifold having a first port for connection to the syringe pump, asecond port for connection to the proximal end of the catheter, and athird port for connection to the low pressure system; and a valve,associated with the manifold, having a first state and a mutuallyexclusive second state; said first state being when the second and thirdports are connected and said first and third ports are alwaysdisconnected; said second state being when the first and second portsare connected and said first and third ports are always disconnected;the valve being normally biased to the first state and being switchableto the second state when fluid pressure from the syringe pump reaches apredetermined pressure level.
 2. The system of claim 1 wherein the lowpressure system includes a pressure transducer connected to the thirdport.
 3. The system of claim 2 wherein the low pressure system furtherincludes a pump for delivering fluid to the third port during a salineflush operation, and for aspirating fluid through the catheter and fromthe second port to the third port during a waste aspiration operation.4. The system of claim 1 wherein the valve is a spring biased spoolvalve.
 5. The system of claim 4 wherein the spring biases the spoolvalve to the first state.
 6. The system of claim 1, furthercomprising:an external motivating source in communication with the valvefor biasing the valve to the first state.
 7. The system of claim 1wherein the valve is configured to be passively biased to the firststate.
 8. The system of claim 1 wherein the valve is configured to beautomatically switched from the first state to the second state whenfluid pressure from the syringe pump reaches a predetermined pressurelevel.